PURPOSE: Testing the new hip joint Helix(3D) efficiency through clinical data and walking parameters. METHOD: Three young hip-disarticulated patients (P1, P2 and P3) were assessed both with their previous prosthesis at first day, then four days and six months after being trained with a new prosthesis equipped with the Helix(3D) hip joint. Assessments comprised a satisfaction questionnaire, a two-minute walk test and a recording of main spatiotemporal gait parameters RESULTS: After four days with the Helix(3D), the satisfaction for the prosthesis was improved for P1, unchanged for P2 and reduced for P3. Distance walked during two minutes increased for P1, unchanged for P2 and slightly improved for P3. Gait pattern was improved in P1, only. P1 abandoned the Helix(3D) at six months due to an ischiatic wound. P2 and P3 chose not to use the Helix at the end of the four days training period because they could not adapt to the Helix(3D) characteristics (hydraulic control of hip extension and assistance to hip flexion) and because they did not gain enough benefits. Despite much effort to adjust the prosthesis, the three patients definitively abandoned the Helix(3D) because of comfort problems, and decided to walk with their previous prosthesis equipped with a monocentric hip joint or even with crutches only. CONCLUSION: The Helix(3D) hip joint may need further developments to get clinically relevant for hip-disarticulated amputees who may also need a long training period to adapt to its technical characteristics.